[quote name='dannybuoy' timestamp='1483695558' post='3209280']
Secondly, and more commonly, some digital pedals might leak noise into the daisy chain which is then picked up by other pedals in the chain. To test this out, put all your known good analog pedals in a chain and then try introducing one digital pedal at a time. Listen for increased hiss, or digital clock noise which sounds like chirping - you might not even have to put the pedal in the audio path to get this, just have it on the daisy chain.
[/quote]
If a digital pedal is creating clock noise on a shared daisy chain, it may be worth threading its power lead a few times through a ferrite core. This creates a small inductance that is invisible to the DC supply, but presents a very high impedance to the problem frequencies. Although these frequencies are too high for us to hear, they can heterodyne with other signals to produce audible noise (sticking my neck out with that one!)
You can get clip-on ferrite cores for a couple of quid from [url="http://www.maplin.co.uk/p/ferrite-clip-on-hem3012-n89ab"]Maplin[/url]: